When a macaque learns to respond to electrical excitation of striate cortex in one hemisphere as a signal to obtain a reward, it immediately responds to similar, test excitation of striate cortex at new loci in either hemisphere. It has been shown that, in the absence of the corpus callosum, the anterior commissure imparts to the contralateral, "test" hemisphere this ability for correct interpretation of the conditional stimulus applied to striate cortex, and that this ability survives transection of the commissure. In other words, the anterior commissure establishes an engram in the "untrained" hemisphere. It is now planned: 1) to block neural transmission, as monitored by evoked potentials, across the anterior commissure by cooling it during all of the monkey's training, and thus determine whether the engram transfer is limited to the training period; 2) to make lesions in various portions of the radiation of the anterior commissure to identify the essential "sending" and "receiving" areas for the engram; 3) to extend the study to interhemisphere relations for imprinting in newly hatched birds and for visual learning in adult birds, focussing on the supraoptic decussation. An heretofore undescribed type of unit activity has been found in striate cortex of unanesthetized squirrel monkeys, and termed "luxotonic" since these units reflect in their maintained rate of discharge the ambient level of illumination. The striate cortex on unanesthetized macaques (and possibly cats) will now be examined to determine the prevalence of luxotonic activity in these species, its distribution in representation of peripheral versus central visual fields and within the magno- and paruocellular laminae of the lateral geniculate nucleus; and whether it is altered by saccadic eye movements which generate no change in visual input. The behavioral and electrophysiological consequences of monocular or binocular deprivation of pattern vision in macaques, beginning perinatally, will be studied under various conditions of attempted recovery.